Green Composites Based on Blends of Polypropylene with Liquid Wood Reinforced with Hemp Fibers: Thermomechanical Properties and the Effect of Recycling Cycles

• Main Authors: Gianluca Cicala, Claudio Tosto, Alberta Latteri, Angela Daniela La Rosa, Ignazio Blanco, Ahmed Elsabbagh, Pietro Russo, Gerhard Ziegmann
• Format: Article
• Language: English
• Published: MDPI AG 2017-08-01
• Series: Materials
• Subjects: Polymer-matrix composites (PMCs); mechanical properties; injection molding; recycling
• Online Access: https://www.mdpi.com/1996-1944/10/9/998

Green composites from polypropylene and lignin-based natural material were manufactured using a melt extrusion process. The lignin-based material used was the so called “liquid wood”. The PP/“Liquid Wood” blends were extruded with “liquid wood” content varying from 20 wt % to 80 wt %. The blends were thoroughly characterized by flexural, impact, and dynamic mechanical testing. The addition of the Liquid Wood resulted in a great improvement in terms of both the flexural modulus and strength but, on the other hand, a reduction of the impact strength was observed. For one blend composition, the composites reinforced with hemp fibers were also studied. The addition of hemp allowed us to further improve the mechanical properties. The composite with 20 wt % of hemp, subjected to up to three recycling cycles, showed good mechanical property retention and thermal stability after recycling.